Effective double Filtration – Features both coarse and fine sponge layers to efficiently remove pollutants from ponds, maintaining clear and water for aquatic life Perfect Compatibility – Specifically designed for filter boxes 52231 and 52229, ensuring a precise fits with easy installation and not additional adjustments needed Sponge Construction– Made from long lasting sponge that is safe, promoting a pond ecosystem Ideal Size – Each filter pad measures 2618x13cm, suitable for most pond and versatile enough to meet various filtration needs Includes 2 pairs of replacement filter pads, offering cost effective maintenance and extended usage for your pond